Compressor vane mounting



Sept- 19, 1961 L. COOPER, JR., ETAL 3,000,552

COMPRESSOR VANE MOUNTING X M24 ,1? Jama 147 TURMEY I IN VENT ORS lea/256% 57, BY fiafi/ .s'a

3,000,552 COMPRESSOR VANE MOUNTING Lewis Cooper, Jr., and Robert B. Koschmann, Indianapolis, Ind, assignors to General Motors Corporation,

Detroit, Mich., a corporation of Delaware Filed May 28, 1957, Ser. No. 660,498 Claims. (Cl. 230-132) Our invention relates to stator constructions of turbomachines such as axial-flow compressors. It provides a structurally simple, readily assembled, and accurate stator structure.

The nature of the invention and the advantages thereof will be apparent to those skilled in the art from the succeeding detailed description of the preferred embodiment of the invention and the accompanying drawings thereof. FIGURE 1 is a fragmentary sectional view of a portion of an axial-flow compressor, taken on a plane containing the axis thereof.

' FIGURE 2 is a cross-sectional view of the case and rotor shroud, taken on the plane indicated by the line 2- -2 in FIGURE 1.

FIGURE 3 is an enlarged view of a portion of FIG- URE 1.

The axial-flow compressor illustrated comprises a case of circular cross-section formed by two semi-cylindrical sections 11 and 12 suitably secured together when the compressor is assembled, by'means immaterial to this invention, at the split lines 13. Successive stator vane rings 14, between which are rotor vane shrouds 16, are mounted in the interior of the case. The rings 14 and shrouds 16 are in semi-circular segments meeting at the plane of the split line. The segments are fixed to the sections of the case so that each half of the stator is a complete assembly before the halves are united.

Rotor wheels 17 including flanges 18 are abutted to form a drum-type rotor, each wheel mounting a row of rotor blades 19. The rotor blades have roots 21 inserted in axial dovetail slots 22 in the wheels and retained in the slots by an expanding split ring 23 engaging in a circumferential groove 24 in the inner surface of the Groove 24 cuts through the base of slots 22, and the ring 23 engages in slots 26 across the bottoms of the blade dovetails. The right-hand wheel 17 in FIGURE 1 is seetioned at the rim between the blade slots, the left-hand Wheel at the blade slot. The rotor structure may, however, be of any suitable character, as this invention is directed to the stator.

Each stator vane segment ring 14 includes a hat section outer shroud 27, radial vanes 28, a channel section inner shroud 29, and a labyrinth seal member 31 fixed to the inner shroud and cooperating with seal ridges 32 on the flange 18. These parts may be brazed together.

The case It) is provided with ribs 33 on its inner surface. These ribs are accurately machined on their inner surface and one side surface. The flanges 34 of the outer vane shrouds 27 rest against the inner surfaces of adjacent ribs, thus precisely locating the vane ring radially and holding it accurately circular.

Each rotor shroud segment 16 comprises a channel section 35 with preferably five blocks 36 brazed into the channel. These blocks are rectangular and are dimensioned for a close fit between machined side faces of adjacent ribs 33 so as to located the shroud 16 axially of the compressor. Shoulders 37 on the blocks are aligned with the outer edge of the channel. These shoulders and the edge of the channel bear outwardly against flanges 34 to hold shrouds 27 against ribs 33.

Each block 36 is drilled and tapped to receive a cap screw 38 which extends through a hole 39 in the case. The five screws 38 hold each segment 16 outwardly Patented Sept. 19, 1961 "ice .. accurately concentric with the case.

' of silver applied to it, which'is soft and thus may be:

cut away by the tips of blades 19 if there is any inter-- The edges of flanges 34 engage the blocks 36 at each side, thus accurately locating the vane ring axially of the case. Ribs 33 provide good support at each edge of the.

shroud 27.

The inner surface of each rotor shroud has a layer 41.

ference. This makes possible an extremely close clearance between blade tips and the shroud, improving com-.

pressor efiiciency. The clearance is greatly exaggerated in the drawings for clarity.

Assembly and disassembly of the stator is 'very easy, and accurate alignment of the parts is assured. The stator vane rings are laid in place, the rotor shrouds are laid over them, and the cap screws are inserted. When each section of the stator is assembled, the rotor is mounted in one section, the other section is put in place, and the sections are joined by a suitable connection along the split line. j

The advantages of the invention in providing a strong; accurately aligned, readily machined and assembled, and light weight stator structure will be apparent.

The invention is not to be considered as limited by the detailed description of the preferred embodiment thereof, as many modifications may be made by the exercise of skill in the art.

1. A stator structure for an axial-flow turbomachine comprising, in combination, a longitudinally split case section of circular arc cross-section having circular arc circumferential ribs on its inner surface, a plurality of stator vane ring segments providing stages of stator blading, each vane ring segment including an outer shroud bearing against the case only at the radially inner surface of the case ribs, rotor vane shroud segments mounted between the stator vane outer shrouds and bearing against the radially inner surface of the stator vane outer shroud, the rotor vane shroud segments including parts fitting between adjacent ribs and locating the rotor vane shroud segments axially of the case section, the edges of the stator vane outer shrouds engaging the said parts of adjacent rotor vane shroud segments to locate the vane ring segments axially of the case section, and means removably connected to the rotor vane shroud segments and case section holding the rotor vane shroud segments against the stator vane outer shroud.

2. A stator structure for an axial-flow turbomachine comprising, in combination, a longitudinally split case section of circular arc cross-section having circular arc circumferential ribs on its inner surface, a plurality of stator vane ring segments providing stages of stator blading, each vane ring segment including an outer shroud of hat section, the flanges of the outer shroud bearing against the case only at the radially inner surface of the case ribs, rotor vane shroud segments mounted between the stator vane outer shrouds and bearing against the radially inner surface of the stator vane outer shroud flanges, the rotor vane shroud segments including parts fitting between adjacent ribs and locating the rotor vane shroud segments axially of the case section, the edges of the stator vane outer shrouds engaging the said parts of adjacent rotor vane shroud segments to locate the vane ring segments axially of the case section, and tension members remoyably connected to the rotor vane shroud segments and case section holding the rotor vane shroud segments against the stator vane outer shroud flanges.

3. An axial-flow turbomachine stator comprising an annular case with circumferential ribs on the radially inner surface thereof and radial grooves between the ribs; stator vane rings having marginal portions bearing against the radially inner surface of the ribs, rotor shroud rings bearing against the radially inner surface of the said marginal portions of adjacent stator vane rings, and having parts extending radially intovsaid grooves and engaging between the ribs to locate the rotor shroud rings axially of the case, the edges of the vane rings bearing against the said parts of adjacent rotor shroud rings to locate the stator vane rings axially of the case, and means connected to the case and the rotor shroud rings holding the rotor shroud rings radially outwardly against the said marginal portions and thereby holding the stator vane rings against the case.

p 4. An axial-flow turbomachine stator comprising an annular case with circumferential ribsvon the radially inner surface thereof and radial grooves between the ribs; stator vane rings having axially-extending marginal portions bearing against the case only at the radially inner surface of the ribs, rotor shroud rings bearing against the radially inner surface of the said marginal portions of adjacent stator vane rings and having parts extending radially into said grooves and engaging between the ribs to locate the rotor shroud rings axially of the case, the edges of the vane rings bearing against the said parts of adjacent rotor shroud rings to locate the stator vane rings axially of the case, and means connected to the case and the rotor shroud rings holding the rotor shroud rings radially outwardly against the, said marginal portions and thereby holding the stator vane rings against the case.

5. An axial-flow turbomachine stator comprising an annular case with circumferential ribs on the radially inner surface thereof and radial grooves" between the ribs; stator vane rings bridging alternate grooves and having axially-extending marginal portions bearing against the case only at the radially inner surface of the ribs, rotor shroud rings bearing against the radially inner. surface of the said marginal portions of, adjacent stator vane ringsand having parts extending radially into alternate ones of the said grooves and engaging between the ribs. to locate the rotor shroud rings axially of the case, the edges of the stator vane rings bearingagainst the said parts of, adjacent rotor shroud rings to locate the stator vane rings axially of the case, and means removably connected to the case and the rotor shroud rings holding the rotor shroud rings radially outwardly against the said marginal portions and thereby holding the stator vane rings'against" the case.

References, Cited in. the file of this, patent UNITED STATES PATENTS n Me.- r-W 

